Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access

ABSTRACT

A telephone station interface is provided with apparatus for detecting when a called party has or is attempting to patch or bridge one telephone call with another telephone call. The detecting of such bridging or conferencing is accomplished through the detection of tones which are commonly associated with such activities, such as a ring signal, a busy signal, special information tones (SIT tones), dual tone multi-frequency (DTMF) tones or so-called Touch Tones, call progress tones, or other tones that occur when calls are placed. The present invention does not have the capability of sensing clicks, pops, or other audio signals associated with the conferencing of multiple communications circuits. The method and apparatus herein are for managing institutional telephone activity, and utilize a computer control unit to control a trunk management unit, which connects institutional telephones to outside telephone lines.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No 08/726,217,filed Oct. 4, 1996, issued as U.S. Pat. No. 5,926,533, which is acontinuation-in-part of application Ser. No. 08/510,327, filed Aug. 2,1995, issued as U.S. Pat. No. 5,655,013 which is a continuation of Ser.No. 08/229,517, filed Apr. 19, 1994 now abandoned.

FIELD OF THE INVENTION

The present invention relates generally to the fields oftelecommunications and penal institution management. More particularly,the invention relates to a computer-based method and apparatus forcontrolling, monitoring, recording and reporting access to outsidetelephone lines in a controlled, institutional environment, such as aprison, military base, hospital, school, business or governmentorganization. Specifically, this invention relates to apparatus fordetecting when a called party has proceeded to bridge together onetelephone call with another telephone call, through the detection ofdial tones, dual tone multi-frequency (DTMF) tones, special informationtones (SIT), ring signals, busy signals, dial tones, other call progresstones, or similar tone signals, without the necessity of sensing ordetecting hook switch or flash signals, which may be problematic.

BACKGROUND OF THE INVENTION

Generally, the need to control access to outside telephone lines in aninstitutional environment is well recognized. In order to preventindividuals from incurring large, unaccountable telephone costs whichthe institution ultimately bears, one must either restrict access tooutside telephone lines or institute accounting controls whereby thecosts of unauthorized calls can be billed to the responsibleindividuals.

Telephone systems in correctional environments require additionalsecurity considerations. Without appropriate controls on telephoneaccess, inmates have been known to use the telephones to harass outsideparties (such as witnesses who testified against them, attorneys whoprosecuted their case, employees of the courts, etc.), to perpetratefraudulent schemes, and to participate in criminal conspiracies (such asarranging the smuggling of contraband into the prison, directing anoutside criminal enterprise, plotting escape attempts or credit cardfraud). Therefore, it is critically important for correctionalmanagement officials to carefully plan, control, monitor and recordinmate access to outside telephone lines.

One of the most fundamental problems—which exists both in correctionaland other business-oriented institutions—is cost control. To achievecost control, it is critical that there be individual accountability foreach call that incurs a charge to the institution. Such accountabilityis typically achieved through use of personal identification numbers(“pins”). Before making a call from an institution telephone, anindividual must enter his PIN. The telephone service provider is thenable to deliver to the institution an end-of-the-month telephone billwhich lists, in addition to the cost of each call, the PIN or name ofthe individual who made the call. From this information, the institutioncan then collect reimbursement from individuals for the costs of certaincalls.

While this system of end-of-the-month call accounting functionsreasonably effectively in a business like environment, it does not workwell in a penal institution. The reason is that inmates show littleconcern for phone bills they can't afford to pay. Thus, the institutionis often forced to absorb the costs of phone calls by its delinquentinmates. Moreover, the fact that account balances are only computedperiodically—i.e., every month, week, or even every day—permits theinmate to accrue large, uncollectible phone bills before his access tothe phones can be terminated. Traditionally, penal institutions haveaddressed this problem by restricting inmates to collect calls only.This, however, still provides the inmates with relatively unlimitedaccess to the outside world, leaving open numerous opportunities forfraudulent and criminal activity, as explained below. Therefore, in apenal environment, it is highly desirable to regulate phone access on anindividual, pay-in-advance basis, and to immediately and automaticallyterminate an individual's phone access when his/her paid-up accountreaches a zero balance.

Another problem in penal institutions is the inmates' desire to makethreatening or harassing phone calls to witnesses, prosecutors, policeofficers, parol officers, psychologists, judges, and the relatives andfamily of such persons. Limiting the inmates' access to collect callsonly, does not effectively address this problem, since an inmate caneasily identify himself (to an operator) as someone from whom therecipient would likely accept a collect call. Rather, one should, at aminimum, provide a means that permits a potential call recipient toidentify the caller as an inmate before accepting the call, whether thatcall is placed on a prepaid or collect basis. Conventionally, this isdone by initially placing the inmate on hold and playing a pre-recordedmessage telling the recipient that a call has been placed from acorrectional facility and that, if the recipient wishes not to receivethe call, he/she should hang up before the call is connected. Thisapproach mitigates, but does not fully solve, the harassment problem. Inparticular, it is still possible for an inmate to repetitively call anoutside party; even if the recipient hangs up after hearing thepre-recorded message, the harassing effect of receiving repetitive callsfrom inside the correctional institution remains. Therefore, it would behighly desirable to provide an institutional telephone system thatautomatically prohibits inmates from attempting to call certain outsidepersons. Moreover, it would also be highly desirable to provide a methodand apparatus for allowing a recipient of an undesired call from aninmate to easily and automatically prohibit all future calls from thatparticular inmate, or from all inmates generally.

Still another concern in correctional institutions is the regulation ofaccess to telephone systems. For various security and managementreasons, it often desirable to restrict a given inmate's telephoneaccess to particular phones, calling times, and to limit the length ofcalls, number of calls, and number of calls to the same number. Also, toenhance security and discipline, it should be possible toinstantaneously revoke an inmate's calling privileges, or to otherwisemodify the extent of a particular inmate's calling privileges.

Correctional institutions also typically wish to monitor and/or recordoutgoing calls. Inmate-to-attorney calls, however, cannot legally bemonitored or recorded. Moreover, certain inmates—those who representparticular security risks—deserve live monitoring, as opposed to mererecording. Thus, it would be highly desirable to have a system whichautomatically initiates the appropriate monitoring and/or recordingdepending upon the identity of the inmate placing a call and therecipient of the call (i.e., attorney or non-attorney). Likewise, it maybe desirable that calls to certain numbers are to be monitored live,while others need only be recorded.

Because the message content of inmate-to-attorney calls cannot belegally recorded or monitored, such calls can serve as a conduit for theinmate's illegal telephone activity. Therefore, it would be highlydesirable to have a system which could passively—that is, without in anyway monitoring or recording what is actually being said—monitorinmate-to-attorney calls to ensure that: (1) the only two peoplespeaking on the line are the inmate and attorney, and/or (2) no DTMFtones, rapid line impedance changes, off-hook conditions or voltagespikes appear on the line. Techniques for voice identification areknown—i.e. U.S. Pat. Nos. 4,993,068, entitled UNFORGEABLE PERSONALIDENTIFICATION SYSTEM and 5,150,357, entitled INTEGRATED COMMUNICATIONSSYSTEM, both incorporated herein by reference—but have not beenpreviously used in penal telecommunications applications.

One patent, U.S. Pat. No. 4,726,057 to Doerry et al. explained many ofthe problems brought about by the deregulation of the telephone industryin the United States. That patent states: “Prior to a June, 1984 FCCdecision, pay telephones were the exclusive province of the variousTelephone Companies while others were precluded from the business ofproviding pay telephone service. Today, however, subject to state PublicUtility Commission regulations, Customer Owned Coin Telephone (COCOT)service is permitted, but a number of non-trivial technical challengeshave been created including called party answer detection.

Coin telephones (pay phones) owned by the local Telephone Companygenerally utilize DC signals to signal called party answer. Suchinformation is specially communicated between telephone central officesand then to the originating pay phone telling it when to accept thedeposited coins. Such information, however, is not communicated toconventional telephones and it is only with great difficulty that calledparty answer can be detected. Naturally, the calling party knows when aconnection is completed; but a knowledge of human frailty suggests thathe not be relied upon to turn the “meter” on.

Complicating the problem of answer detection is the existence of specialinformation messages that are provided when, for example, a telephonehas been disconnected or a new telephone number has been assigned; andwhile certain tones are indicative of a proper answer, other tones arenot. Ringing, busy and reorder signals as well as background noise andfeedback from the calling party herself (sidetone) make answer detectiona formidable challenge.”

The problems set forth above are exacerbated by the fact that callers,such as inmates in a prison, have the ability to work in concert withothers outside of the facility. For example, an inmate may be restrictedfrom calling a particular judge who sentenced him, however, that inmatemay call his spouse, who in turn may set up a conference call to thejudge, thus allowing the inmate to verbally abuse the judge. Such aconference call may be prohibited by law, however, the correctionalfacility cannot prevent it, as the called party, in this case, thespouse, has the ability to bridge callers with other outside,unrestricted telephone lines, thus giving the inmate unrestrictedtelephone access.

Present attempts to solve the problem of called party bridging, orso-called third party calls, have shortcomings. For example, one attemptat resolving this problem is disclosed in U.S. Pat. No. 5,319,702, toKitchin et al. In that patent, the need to provide an apparatus for usein conjunction with so-called “local equipment/telephone.” When thelocal equipment/telephone is in telecommunication with a remotetelephone, (i.e., when a telephone call is established therebetween),the apparatus is capable of indicating whether the remote party hasperformed a specific act causing the generation of a hook flash-typesignal which is detected by the apparatus. In that patent, the detectionof a hook flash-type signal is presumed to solve the problem ofunauthorized calls to third parties, such as a telephone call from aninmate to the judge who sentenced him, as set forth above. The apparatusof that patent includes a band filter for passing energy having certainfrequencies and an energy detector for detecting a specific electricalenergy pulse having been filtered by, i.e. passed through the filter,and having a predetermined minimum magnitude. The apparatus of thatpatent further describes in part software (referred to as windowanalyzation means) which cooperates with the energy detector to detect aspecific event(s) occurring on the telephone line during a predeterminedmaximum time window following the detection of a specific pulse on thetelephone line, i.e., when a telephone call is in progress between thelocal party/equipment and the remote party. The detection of a specificevent(s) on the line provides an indication as to whether the remoteparty has performed a specific act such as (1) attempting to initiate a3-way conference call, (2) accepting a call or the charges therefor, (3)terminating a call before the local equipment/party terminates the call,and (4) dialing a specific number on a remote rotary/pulse telephone.Further, the apparatus of that patent is said to be suitable for use ina computer controlled telephone wherein the energy detector detects whena called party has answered a call initiated by the computer operatedtelephone and dialed a pulse/dial telephone or activated (flashed) thehookswitch. The energy detector is said to do this by measuring incomingelectrical signal energy in a particular frequency band. Then, accordingto that patent, the software window analyzer cooperates with the energydetector to provide efficient and reliable protection of a calledparty's pulse dialing of a digit (usually a “zero”) to verify the calledparty's acceptance of a call or a collect call or the called party'sattempt to activate 3-way calling by flashing the called party'stelephone hookswitch.

The energy detector of U.S. Pat. No. 5,319,702 to Kitchin et al. is alsosaid to include an absolute value level detector circuit that determineswhen an energy pulse having passed through the band filter is above apredetermined level. If above a predetermined level, the information istransmitted by the energy detector to the apparatus' controllingcomputer. As previously mentioned, the apparatus further includessoftware, i.e., the aforementioned window analyzer, for cooperating withthe energy detector to detect specific event(s) occurring on thetelephone line during a predetermined maximum time window following adetection of the specific pulse. In the situation where the apparatusaccording to that patent is said to be designed or programmed to detecta remote party's attempt to initiate a 3-way conference call, thesoftware window analyzer is said to include a timer or timer means forcooperating with the energy detector so that the timer begins runningfor a first predetermined period when a specific energy pulse isdetected by the energy detector. The software window analyzer alsoincludes sound detection means for detecting sound on a telephone lineand for cooperating with the timer so that the sound detection means isactivated at the end of the first predetermined period for a secondpredetermined maximum time period. If sound is not detected during thesecond predetermined time period, such indicates that the remote partyhas attempted to initiate a 3-way conference call.

Kitchin discloses a type of energy detector that can also incorporate aringback detector—not to activate third party call blocking, but merelyfor activating the energy detector when the ringback signal is detected.Thus, the ringback detector is used to set the energy detector, so thatthe energy detector can purportedly carry out the purpose of thatpatent, and so that the energy detector can be utilized. Indeed, Kitchinstates that “[t] hose skilled in the art will appreciate that calledparty answer is indicated when the first specific energy pulse isdetected after the apparatus has detected the called party's ringbacksignal.” Thus, the ringback signal is used to initialize the Kitchinsystem—not to solve the problem at hand. In that sense, Kitchin teachesaway from relying upon the use of ringback detection as a means to blockthird party calls.

The Kitchin patent discloses “being useful for detecting certainspecific events, i.e., call answer, an attempt to initiate a 3-wayconference call, call acceptance, call termination, and determining thespecific number dialed number on a rotary/pulse telephone. Any eventwhich causes the generation of the hook flash-type signal such as a callwaiting signal can purportedly be detected. Importantly, Kitchin saysthat it can detect “any event which causes the generation of the hookflash-type signal”. This is important because that is the entire focusof the Kitchin patent—to detect hook flashes, or the energy pulsesassociated therewith. This approach is problematic, as it relies on thedetection of a pulse—not the detection of certain tones. While theKitchin patent may appear to be an elegant solution to the problem ofblocking third party calls, it is needlessly complex, and if anything,complicates the process of detecting the attempted establishment ofthird party calls. The prior art does not teach the simple, directmethod of sensing third party call patterns by merely monitoring theoccurrence of tones that called parties traditionally generate in theirefforts to bridge callers with third parties. In essence, many calledparties allow the caller to be on the line while they dial the thirdparty—that is an opportunity to sense DTMF tones. Then, many calledparties may dial the wrong number of the third party, and a SIT tonewill indicate that number may have been disconnected, subject to an areacode change, or the like—all while the caller is on the line. That isanother opportunity for sensing tones to prevent third party calls.Also, called parties may use a credit card to call third parties—alsowhile the caller is on the line. Call progress tones may be generatedduring such credit card calls—thus, yet another opportunity to sensetones to prevent third party calls. Also, if at any time during thecall, a ring or busy signal is heard on the caller's telephone, stillanother opportunity is present for sensing tones to prevent third partycalls. And finally, if at any time during the call while the inmate ison the line, a dial tone occurs (as when a called party may go off-hookto place the call to the third party), yet another opportunity existsfor sensing tones to prevent third party calls.

SUMMARY OF THE INVENTION

In light of the above, one object of the invention is a method ofmanaging telephone activity in an institutional environment to achieveimproved security and reduced cost. Another object of the invention is asystem adapted to perform such improved institutional telephonemanagement.

Yet another object of the invention is a method and apparatus forpassively monitoring a telephone connection to detect security breaches.

A still further object of the invention is an institutional telephonemanagement system wherein the parameters that control the operation ofthe system as well as the records of system activity are stored in acentral database, thereby permitting simple customization of systemoperation, generation of reports and monitoring of status.

In accordance with one aspect of the invention, a method of managingtelephone activity in an institution includes the steps of: (1)identifying an institutional caller (the “calling party”) who wishes toplace an outside call to an outside recipient (the “called party”); (2)blocking the institutional caller and —while the institutional caller'sline (earpiece and/or mouthpiece) remains blocked—(a) calling saidoutside recipient (called party), (b) providing the identity of saidinstitutional caller to said outside recipient and © receiving a controlcode from said outside recipient; (3) determining, in response to saidcontrol code, whether to connect the institutional caller to the outsiderecipient, and optionally, whether to indicate any of a plurality ofmessages to the calling party, e.g., an inmate, and (4) terminating orotherwise tracking or accounting for calls to third parties wherebyattempts are made by the called party to bridge or conference thecalling party (the caller or inmate) with any third party.

In accordance with another aspect of the invention, an apparatus formanaging telephone activity in an institution includes: a plurality ofinstitutional telephones located within the institution; a trunkmanagement unit (TMU) for selectively connecting the institutionaltelephones to one or more outside telephone lines, wherein the TMUincludes means for decoding DTMF tones generated by the institutionaltelephones or received from the outside telephone lines; and a computercontrol unit (CCU), coupled to the TMU, for controlling the connectionof the institutional telephones to the outside telephone lines basedupon DTMF tone(s) received from the outside telephone lines. A databaseassociated with the CCU contains information regarding the callingprivileges of each person within the institution. In a preferredembodiment, the TMU—prior to connecting the call—plays an announcementto the called party identifying the institution and caller, along withthe options available to the called party. In response, the called partymay enter the announced DTMF tone sequence (preferably GOTU), whichmodifies a record in the database, thereby prohibiting the caller(and/or other similarly situated prospective callers) from calling thecalled party in the future.

Other features of the TMU provide security and monitoring functions. Theinvention provides three levels of monitoring, any or all of which maybe active for any given call. The first level is “live” call (voice)monitoring, where the prison officials actively listen to a live call.The second level is call recording. The TMU can be programmed to enableassociated recording equipment to record telephone calls. The thirdlevel is “passive” line monitoring, where the TMU detects, for example,DTMF tones, off-hook conditions, voltage spikes and/or sudden lineimpedance changes, in order to thwart attempts at unauthorized three-waycalling, call conferencing, call transferring, call forwarding orre-dialing via various alternate common carriers, many of whom now offer“1-800” or local telephone number (e.g., “950”) access numbers. Also,care is taken to avoid disrupting calls that do not represent securitybreaches, by preventing false triggering of the above “passive” linemonitoring features. For example, with respect to DTMF tone blocking,the TMU will look for any additional digits entered by an institutionalcaller, such as an inmate, to prevent the inmate from redialing to othertelephone numbers that may not be authorized. However, to prevent“talkoff”, whereby the normal telephone conversation can falsely triggera disconnect signal (because the TMU may interpret the conversation asDTMF dialing), the TMU can be set to look at the number of digits dialedwithin a specified time period (e.g., six (6) digits within a fifteen(15) second time period, or any variation of the two parameters) andthereby, determine whether the audio information is indicative ofunauthorized DTMF redialing or just a normal speech or voice pattern.

In accordance with the preferred embodiment of the invention, all callsare passively monitored and all calls that can be legally recorded—i.e.,all but inmate-to-attorney calls—are recorded. At any time, prisonofficials can selectively invoke live monitoring to listen in on anycall in progress, except an inmate-to-attorney call. System alarms,which trigger any time a particular inmate places a call or calls acertain person, allow officials to determine when live call monitoringis appropriate. Likewise, the telephone system of the present inventioncan be programmed to default in any manner. For example, the system canbe set to place only those telephone calls that are among a pre-approvedlist of telephone numbers. Conversely, the system can be set to placeall telephone calls except those that are among a list of restrictedtelephone numbers. Optionally, the telephone system of the presentinvention can include speed-dialing, whereby upon entering a PIN, forexample, an inmate can enter “11” followed by the “#” key. In that case,the prison administrator may have established that “11” is thespeed-dialing sequence for that inmate's mother. Of course, the systemcould be configured so that the inmates themselves can program thetelephone system with speed-dialing digits, however, a principalobjective of speed-dialing is to save time at the telephone, thus makingthe telephones available to the largest number of inmates in theshortest possible time period.

In addition, the invention may include biometric voice verificationfeatures. The TMU, for example, may digitize a sample of the caller'svoice. The CCU then compares the digitized sample with a stored voiceprint, to verify the identity of the caller. Such biometric monitoringmay also be used in a passive call monitoring mode, wherein periodicsamples of the caller's voice are provided to the CCU—and checkedagainst a list of authorized voice prints—to ensure that no unauthorizedcallers are participating in a call, and to ensure that inmates are notsharing or selling relatively liberal calling privileges associated witha particular PIN or inmate account to other inmates that are subject tomore limited calling privileges. The use of biometric voice verification(or “voice prints”) can prevent PIN abuse in general. For example, if aparticular inmate with restricted calling privileges, or no availablefunds, attempted to force (e.g., by threatening physical attack) anotherinmate with relatively non-restricted calling privileges (or availablefunds) to turn over his PIN, biometric voice verification would obviatethis problem, as the voice would be used to validate entry into anyinmate account.

The principal feature of the present invention is the implementation ofa way to detect inmate or other regulated caller telephone calls tocalled parties, whereby said called parties act to bridge the inmate orregulated caller to some third party. Whereas regulated callers, bydefinition herein, are only permitted to communicate with certain calledparties, the authority in charge of the caller or inmate's calls areafforded the ability of preventing called parties from bridgingtelephone calls from inmates or other regulated parties to unauthorizedor unknown third parties. Said authority has, at its option, the abilityto prevent, terminate and/or track or monitor any of said attempts.

Broadly, the present invention takes the form of an apparatus and methodfor detecting and identifying disparate preselected signal sequences ofspaced tone bursts. Such spaced tone bursts or tone signals may beoriginated by the called party in a called party's effort towardbridging the caller or inmate with a third party. Such tones are thetones often generated during such bridging attempts, such as the ringingof the third party's telephone, a busy signal during the attemptedcalling of a third party by the called party, a dial tone as the calledparty is dialing the number of the third party, SIT tones generated whenthe called party attempts a telephone call to a third party whose numberhas been, for example, disconnected, other call progress tones, such asthose associated with telephone credit card usage, other DTMF tones, forexample, those used by the third party to call the third party in thefirst place, and any other tones, thus obviating the need for anydetection of hook flashes or other clicks and/or pops on the telephoneline, that may unreliably be associated with attempts by called partiesto place telephone calls to third parties.

In some further specific aspects of the invention, logic circuitrycomprises gates and registers. The latter is used to store durations oftone bursts and spaces which the gates compare for consistencies with apreselected signal sequence. Further gates are utilized to detect one ofa plurality of preselected error conditions. Occurrence of an errorcondition is used to override indication of a valid signal sequence andto identify possible malfunctions in apparatus used to generate thepreselected signal sequences. The storage of certain tones may bedesired, for example, with ring or busy signals. As those tones areoften associated with specific cadences (ring ⅔ on, ⅓ off, and busy 50%on, 50% off), the sensing of cadence in addition to tone frequency canimprove system reliability. The detection of tones can be accomplishedby certain integrated circuits, such as the Teltone brand series ofchips, designed to detect and digitally decode DTMF and/or SIT tones.Typically, DTMF tones are the 12 conventional Touch Tones (1-9, 0, # and★), and SIT tones are generated by the local central office equipmentwhen a call does not go through, for example, if a number is blockedfrom a particular telephone number, a number is no longer in use, anumber has been disconnected, an area code has been changed, etc. Withthe present invention, such tones (DTMF or SIT), or other tones (dial,ringing, busy or call progress tones) are used to signal an inmate orother regulated telephone system that a called party (a party called by,e.g., an inmate) is attempting to bridge that telephone call togetherwith some unknown and/or unauthorized third party. Upon the detection ofsuch a tone (call progress tone or other tone), the present inventionmay either terminate the call between the inmate and the called party,or may evaluate what third party was called, to attempt to validate sucha third party call.

Also, with the present invention, the third party call attempt may bestored, for present or future review by an institutional authority, andpatterns may be monitored, so that prison officials may considercurtailing future inmate calls to particular called parties. Thus, thirdparty call attempts can be tracked, both on a per inmate and on a percalled party basis.

Thus, if inmates A through G all know to call a certain called party Xso that called party X can bridge them to their respective unauthorizedthird parties, then, the prison officials will know that future calls toparty X are to be blocked, regardless of who is initiating such a call,because called party X is suspected of being an individual whofacilitates unauthorized third parties. Importantly, certain calledparties may even attempt to bridge a call from one inmate to anothercall from another inmate. In that instance, keeping track of suchattempts, and terminating such calls, is particularly important, asinmates within the same institution may be conspiring to do crime, suchas breaking out of prison.

The present invention relies on some of the same circuitry used bycertain customer owned coin operated telephones (COCOTS) and otherfacility based PBX equipment. Some such pay telephone stations areprovided with apparatus for detecting when a called party has answered acall (initiated at the coin telephone station) by tracking call progresstones, and sensing tone cadence. The apparatus of the present inventionmay also include circuitry for inhibiting the indication of called partyanswer when a sequence of three predetermined (such as SIT) tones arereceived; such tones generally precede an intercept message such as onethat announces that a telephone number has been changed or disconnected.The apparatus further includes circuitry for inhibiting the indicationof called party answer when call progress tones are detected. Finally,the present invention can sense DTMF tones themselves, often used in thecompletion of calls by Touch Tone telephones.

The present invention thus obviates the need to rely on sensing clicksor pops associated with attempts by called parties to bridge calls viaconference call circuitry or call waiting. Such reliance isdisadvantageous. First, depending upon the local exchange carrierswitch, call waiting and call conferencing, as provided by the telephonecompanies, may not even generate any click or pop (or other suitablepulse that could activate the Kitchin circuitry). Also, the circuitry ofKitchin is susceptible to false triggering, as it senses impulses thatcan occur randomly. To the contrary, applicant contends that theinvention set forth herein is simpler and more accurate, certainlyinsofar as false triggering is concerned. Applicant contends that thesensing of tones exclusively as a means to restrict third party callswill lead to far less false triggering as compared to the Kitchinproposal. As applicant's invention is not directed to sensing thirdparty call attempts that do not involve tones, applicant senses onlytones—not impulses associated with hook flashes, as Kitchin requires. Tothe contrary, applicant contends that the present invention obviates theneed for that by sensing other criteria that may be indicative of anattempt by a called party to bridge one telephone caller with another.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description below describes the preferred embodiments ofthe invention and is intended to be read in conjunction with the set ofdrawings, in which:

FIG. 1 is a block diagram showing the major components of a preferredapparatus, including a plurality of institutional telephones, a computercontrol unit (CCU) and a trunk management unit (TMU);

FIG. 2 is a block diagram showing the software and firmware architectureof the TMU/CCU apparatus;

FIG. 3 is an exemplary screen showing an institutional user's callingprivileges and activity;

FIG. 4 is a block diagram of a TMU;

FIG. 5 is a block diagram of a TMU and CCU/CPU configured which permitsthird party calls to be detected; and

FIG. 6 is a flow diagram depicting the operation of applicant's thirdparty call detection system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiment(s) will be described with reference to prisonbased call management. This, however, should not be viewed as limiting,since the invention is also applicable in other institutional settingssuch as military bases, schools, mental institutions and businessorganizations.

Referring now to FIG. 1, a call management system manages calls from aplurality of inmate telephones 1. A TMU 2 controls the connection ofindividual inmate telephones (for example 1 a) to outside telephonelines 8, and electronically monitors connected calls. A TMU 2 canoptionally contain (and/or be connected to external) voice messaging orvoice synthesis equipment, to facilitate features such as over-the-phonevoice prompting, voice mail, or any voice activated, responsive orinteractive telephone feature. For example, an inmate could enterhis/her PIN into a telephone 1 keypad, and then, access his/her account.In turn, voice equipment associated with or contained within the TMUcould inform the inmate of the exact balance available in his/heraccount for future telephone calls. Additionally, the inmate couldascertain how much any prior telephone call has cost, and further, coulddial an intended telephone call, and ascertain how much that call willcost for the first time period (e.g., the first minute), or, find outhow many minutes the inmate can be connected to that telephone number,given the cost of that call and the amount remaining in the inmate'saccount, all prior to actually completing the call and becomingobligated to pay for it. Obviously, for debit-based systems, inmatecalls will not be placed in the event that sufficient funds are notavailable. Further, if during a call connection, inmate funds becomenearly exhausted, a warning tone could inform the inmate of thatcondition, so that the inmate can terminate the conversation, and takeappropriate steps to replenish his/her account. Such warning tones couldbe made possible by a real time call cost monitoring system, thatcompares inmate call costs and inmate account balances while each callis in progress.

A serial interface card 4 digitally interfaces TMU 2 to: a CCU 3, one ormore administrative terminals 5 a-b and, via data modems 6 a-b, and to aremote terminal 7. Of course, remote terminals 7, administrativeterminals 5 and CCUs 3 can be connected via so-called dedicateddata/telephone line services, obviating the need for actual modems 6.Alternatively, TMUs 2 may share a common local area network. Such analternative structure can accommodate data transfers, digitized voicesignals, data packet transmissions, call processing data, and the like.In such an alternative embodiment, the local area network may evenfacilitate packet communications between individual TMUs or the TMUs andtheir respective hosts.

TMU 2 communicates bi-directionally with CCU 3. In one direction, CCU 3directs TMU 2 to connect, record, passively monitor and terminate calls,and to download and/or play prerecorded messages to an inmate or outsidecall recipient. In the other direction, TMU 2 monitors the real-timestatus—i.e. off-hook, DTMF tones, voltage spikes and rapid impedancechanges—of institutional and outside telephone lines. In addition, TMU 2can provide digitized voice samples to CCU 3 in order to record messages(such as the inmate's name) and to support biometric voice verificationor monitoring functions. Optionally, TMU 2 (or other comparableapparatus) could be LO configured to provide digitized voice samples to,for example, CCU 3, for each call made, whereby such samples aresufficient in length to provide verification that the inmate indeedparticipated in a conversation with a particular called party on aparticular date and at a particular time. Because prison administratorsmay not wish to charge inmates (or in the case of collect calls, calledparties) for certain calls (for example, calls the administrator deemsincomplete), it is critical that administrators have the ability toverify actual telephone communications. Incomplete telephone calls mayinclude, for example, busy signals, calls that do not “go through”,calls that are not answered (as distinct from calls that reach answeringmachines, which may be deemed complete), etc. Thus, if an inmate or acalled party subsequently claims that a particular telephonecommunication never occurred (e.g., a busy signal was reached, thecalled party never answered, or no voices were spoken at all), theprison administrator can retrieve the voice verification record toevaluate whether, e.g., a credit is due, telephone system repair isrequired, or whether claims that certain calls were incomplete arefalse.

Referring now to FIG. 2, CCU 3 is preferably a “486” personal computeror larger “super-mini” type computer configured to operate under asuitable operating system, such as UNIX™ System V. Of course, any numberof operating systems will be suitable for the purpose of the presentinvention. In addition to the operating system, a database managementsystem (DBMS), such as ORACLE™, which includes a structured querylanguage (SQL) interface, is used to store system configuration andstatus information. A SQL forms generator provides access to the storedconfiguration and status information. A SQL menu program allows users toeasily navigate the database system. A SQL report writer is used togenerate reports of calling activity or other system usage.

TMU firmware controls the operation of TMU 2. TMU interface software inCCU 3 is configured to manage communication between TMU 2 and CCU 3.ORACLE interface software provides a simple, menu based interface tofield users such as correctional officers and management officials.Real-time control software manages the real-time activity of the systemand responds to communications from TMU 2 and user inputs from CCU 3 orterminals 5 a-b and 7.

From an administrator/user perspective, the CCU software supports thefollowing general functions:

(1) establishment and configuration of individual inmate data andmonetary accounts;

(2) checking of inmate debit (i.e. paid-in-advance) accounts;

(3) setting of global (i.e. institution wide) and individualrestrictions on telephone access;

(4) real-time monitoring of inmate telephone calls and alerts (based oncall content, security breaches, etc.), along with the ability to cutoff inmate calls individually or globally;

(5) storing and reporting of detailed inmate call details and accountinformation; and

(6) storing and reporting of telephone usage data.

Referring now to FIG. 3, an exemplary form 30 provides easy access tovarious information regarding an inmate's debit account, callingprivileges and calling activity. The FIG. 3 form includes a titlesegment 31, which displays the current date, title of the form and formcode. Below the title segment is a header segment 32, which typicallydisplays such information as the inmate's name, registration number,preferred language selection, prisoner account code (“PAC”, or PIN),certain calling privilege information and account balance. Below theheader are a plurality of data blocks 33, which show the inmate'stransactions (both accounting transactions and phone calls) as well ashis/her calling privileges and restrictions—i.e., numbers the inmate isallowed to call, the inmate's attorney's number, numbers the inmate isprohibited from calling, and numbers which should trigger an alert onthe system terminals when a call is attempted. The system allows theuser to scroll through the data blocks in order to bring any particulartransaction or restriction into view. A help line 34 lists the commandsavailable to the user. A bottom positioned status line 35 completes theform. Form 30 may be expanded as desired to facilitate keeping track ofwhich inmates have attempted to call called parties, who in turn make aneffort to conference in a third party. Where the called party has theinmate on the line while the called party dials the third party, the TMUmay sense the telephone number of the third party, and record thatinformation as well in form 30. Thus, form 30 may contain a listing ofthe called numbers (as in segment 33), and may also contain the numbersthat the called parties attempt to bridge together with the inmate.Also, other forms like form 30 may be generated on a per third partybasis. In that manner, if multiple inmates tend to call the same calledparty, and that called party tends to bridge inmates to unauthorizedthird parties, including even to other inmates, the prison officials canread such a report, on a per third party and/or even called party basis,to evaluate whether to restrict inmate calling privileges, and toevaluate whether to restrict calls globally to one particular calledparty.

Referring now to FIG. 4, a block diagram of one channel of amultichannel TMU 2 is shown. Generally, TMU 2 includes circuitry toselectively connect inmate phones with outside lines, to selectivelymonitor and record the connection, and to generate appropriate voiceinstructions or prompts to the inmate and/or the outside call recipient.

As depicted in FIG. 4, a channel of TMU 2 connects to an inmatetelephone 1 at a station input line 40. A record blocking circuit 41connects station input line 40 to recording equipment (not depicted) vialine 41 a (which line can also be used for “live” call monitoring). CCU3 automatically controls an attorney relay 41 b and, in the case of aninmate-to-attorney call, switches line 41 a to a tone generator 41 c,thereby blocking improper attempts to record or monitorinmate-to-attorney calls.

A split relay 42 switches the inmate telephone between a local line 42 aand an outside line 42 b. Initially (i.e. before the inmate initiates acall), split relay 42 connects station input line 40 (via local line 42a) to a monitor circuit 43, which monitors the inmate's telephone.Monitor circuit 43 supplies a battery feed to the inmate's telephone,and performs pulse digit recognition and current detection as well. Adial tone generator 43 a (which is preferably common to all channels ofthe TMU) supplies a dial tone to the inmate's phone. A relay 44 aswitches a DTMF receiver 44 to decode tones on the local line 42 a orthe outside line 42 b. A voice-out-station line 45 a supplies voicemessages to the inmate's telephone. CCU 3 controls the decoder portionof an integrated coder/decoder (CODEC) circuit to generate the messagesfed to line 45 a. (The decoder portion of a second CODEC also drives avoice out central office line 45 c to play messages to outside line 42b.) A central office voice input line 47 b connects to the coder portionof the CODEC circuit to support message recording, voice monitoringand/or verification functions. Optionally, voice-in-station 42 c is usedto record the name of an inmate. Also optional, answer board line 47 gis used to detect called party answer conditions, by detecting thepresence or loss of call progress tones (e.g., ringing, busy,special-information-tones (SITs), etc.).

A hold circuit 46 is used to interact with the outside caller during thecall qualification process, during which the station input line 40 isswitched to local line 42 a. A hold relay 46 d selectively connects holdcircuit 46 to outside line 42 b. A DTMF generator 46 c (preferablycommon to all channels of the TMU) is controlled by CCU 3 to, forexample, place an outside call to a requested number. Hold circuit 46interfaces with DTMF receiver 44 to detect tones generated by theoutside caller during the call qualification process. The hold circuit46 (with its associated relay 46 d) can also pass audio informationdirectly to the monitor circuit 43 as desired via audio feed throughline 46 b. The hold circuit 46 can also be used for dialpulse dialing tothe central office. Line current detector 47 a (preferably implementedusing an opto-isolator), ring detector 47 e, and tip/ground detector 47d monitor the status of outside line 42 b. Ground start relay 47 fconnects a ground start circuit to the ring wire of outside lines 48 aand 48 b, to start “ground-start” type lines. A line relay 48 switchesoutside line 42 b between a central office main line 48 a and a centraloffice auxiliary line 48 b. Also shown are voice out (45 c) and voice in(47 b) ports, and a ground start (47 c).

In addition to the channel circuitry described above, TMU 2 iscontrolled by a microprocessor 49 a, which interfaces with a watchdogtimer 49 b and with a memory 49 c, channel I/O 49 d, miscellaneous I/O49 e and dual serial ports 49 f via data, or so-called “glue” logic 49g. TMU 2 also includes a jack tester circuit 49 h and connectors 49 iand 49 j to answer and voice boards, respectively. The voice boardcontains a plurality of integrated CODECs (preferably two per TMUchannel) as well as circuitry needed to permit CCU control of theCODECs, including I/O circuitry and voice data buffers.

Referring now to FIG. 5, a block diagram of a TMU 2 and CCU/CPU 3 areconfigured to permit third party calls to be detected. The TMU 2includes or is interfaced to (as shown in FIG. 4, via connectors 49 iand 49 j) an operator board 400 and an answer supervision board 420. Theanswer supervision board 420 detects specific tone frequencies, andsends messages to the operator board 400. The answer supervision board420 is capable of detecting the presence of any tones of interest,particularly with respect to the present invention, tones that may beindicative of attempts by a called party to place calls to thirdparties, so that the called party can bridge the caller or inmate with athird party, including unauthorized third parties. Of course, someinstitutions will prohibit all calls to all third parties.

Specifically, answer supervision board 420 will detect certainfrequencies of interest. First of all, the answer supervision boardshould be able to detect dial tones, which are typically tonesconsisting of components at 350 & 440 Hz. Also, answer supervision board420 should be able to detect busy signals (a combination of 480 & 620Hz), ring signals (440 & 480 Hz), and the like. Thus, at least fourfrequencies are of interest (350, 440, 480 and 620 Hz). In addition, theanswer supervision board 420 may contain or may be supplemented byhardware such as the Teltone brand chip suitable for sensing anddecoding DTMF tones, SIT tones, other call progress tones, such ascredit card validation tones, and the like. In that manner, answersupervision board 420 or other similar hardware and/or software can beestablished to detect tones indicative of attempts to complete thirdparty or three-way telephone calls.

The operator board 400 communicates with the answer supervision board420. The operator board determines pulse width and the edges on thetones. Also, as the operator board interfaces directly with CPU/CCU 3,operator board 400 must ignore tones which occur prior to the calledparty answering the telephone. If not, it is possible that the ringingof the called party (which is permissible) may disconnect the inmate.Thus, the monitoring of third party calls should preferably commenceonly after the called party answers the telephone.

Finally, CPU/CCU 3 is responsible for interpreting detected tones andtaking the appropriate action. For example, CCU# may disconnect a callto a caller upon sensing a dial tone. It may also record the number thecalled party attempted to connect the inmate to, and it may record thenumber of the called party (of course). It may keep track of callhistory on a per inmate, per caller, per called party basis, and thelike. The CCU 3 may compare the third party calls to a list ofauthorized calls. For example, if one particular inmate calls hisattorney (a permitted call), and that attorney has received permissionto set up a conference call with that inmate's physician, then, CCU 3can be programmed to permit that caller (the attorney, based on theattorney's telephone number), to conference in only that physician(based on that physician's telephone number). In that manner, some thirdparty calls could be permitted, while other are not. Also, with such amechanism, it is contemplated that at one level, all third party callsare prohibited. Consequently, by hardware and/or software, all thirdparty calls will be blocked, by applicant's invention or other methodsof accomplishing the same result. Then, by applicant's invention, thecalled party will be responsible for keeping the inmate on the line (viaan audio communication pathway), so that the inmate can “hear” the DTMFtones that the called party is dialing, to reach the third party. Inthat manner, the telephone number of the third party can be comparedwithin the CCU against a list of approved third party number for thatinmate, and the CCU 3 may permit such a third party call, by overridingthe blanket prohibition of all third party calls, for that one instance.In that manner, some third party calls may be permitted, and others not.Of course, the prison authorities may specify any level of prohibitionor permissive third party calling, and the CCU 3 can be programmed tohandle any level, and keep track of any level.

The CCU 3 can also handle other functions, such as taking appropriatemeasures in response to certain tones. Also, the tones may be monitoredfor their frequencies, pulse widths and even period, duration, cadences,etc. For example, busy signals are often a 50% on, 50% off cadence,while ring signals are usually 33 and a third percent on, and 66 andtwo-thirds percent off. Thus, CCU 3 can be used to detect signalcharacteristics, such as cadence, to ensure that the correct tone signalhas been interpreted.

FIG. 6 is a flow diagram depicting the operation of one example ofapplicant's third party call detection system. The answer supervisionfirmware 600 senses whether a tone has been detected (602). If so, theduration of the tone is sensed, and if over 120 ms (604), and under 5000ms (606), then a message (608) is sent to the operator firmware (620).It will be recognized that the operator firmware (620) corresponds tothe operator board (400), while the answer supervision firmware (600)corresponds to the answer supervision board (420). If the operatorfirmware (620) receives a message (622) form the answer supervisionfirmware (600), and if the called party has answered his or her phone(624), and if the call lasts beyond 5 seconds (626), a message (628) issent to the 3-way call monitor program (640), which is implemented byhardware, such as CCU 3 and software. Program (640) senses messages(642) from the operator firmware (620), and if a message was received,certain decisions and actions are taken. First, two tones must bedetected (644) by the answer supervision firmware (600). This is sobecause dial tones, ring tones, busy tones, SIT tones, DTMF tones, callprogress tones, etc., are all two-frequency tones, and hence, step (644)filters out those tones that are mono-tones. Also, particularly withrespect to ring signals and busy signals, the cadence can be sensed(646), and if a match is found, the call can be cut-off (648) and ended(650), and the TMU 2 can be released (652).

Naturally, many variations of this apparatus are possible, so that anyparticular tone sequence can effect any desired operation. Also, recordsof call history, attempts to bridge calls, and any other statistics, canbe kept as well, as CCU 3 can be a computer with any desired database.

Generally, the method of connecting an inmate call was discussed in theparent applications hereto, Ser. No. 08/510,327, filed Aug. 2, 1995,which is a continuation of Ser. No. 08/229,517, filed Apr. 19, 1994,herein incorporated by reference.

TMU 2 continuously monitors the inmate telephones 1. To place a call, aninmate picks up a phone and enters two numbers (in any order establishedby the facility): (1) his/her personal identification number (PIN); and(2) the number to be called. TMU 2 forwards both numbers to CCU 3,which, in turn, queries the inmate's account to check whether:

(1) there are sufficient funds in the inmate's debit account to make thecall (unless the call is a collect call);

(2) the particular inmate is allowed to: (a) use the particulartelephone extension; (b) place calls at the given time-of-day; or © hasexceeded a maximum number of calls or calling minutes within a givenperiod of time; and

(3) based upon the number to be called, whether the number is approvedor prohibited, whether the number to be called corresponds to theinmate's attorney (in which case, the conversation will not be recordedor “live” monitored), and whether there are any time-of-day or callfrequency or other restrictions on the number to be called.

If the call is rejected on the basis of (1)-(3) above, CCU 3 directs TMU2 to play a message to the inmate (in the inmate's preferred language,determined by his/her PIN and established when the prisoner first entersthe facility) explaining the reason that the call has been rejected.Assuming that the requested call has passed these initial screeningtests, CCU 2 directs TMU 2 to call the destination party. Untilcompletion of these steps, the inmate's earpiece and mouthpiece remainblocked (with respect to the called party), thereby eliminating theinmate's opportunity to interject offensive or harassing remarks.Subsequently, the destination or called party receives the call andhears a prerecorded message which identifies the institution, caller andgives instructions as to how the called party may elect to receive thecall and how the party may block future calls, if desired. The messagemay also state that third party calls are prohibited for this inmate (ifthat inmate is restricted from third party calls), or the message mayindicate that third party calls are prohibited for all inmates at thatinstitution. Also, the message could ask for an authorization code,which the caller can enter, to override the third party blockingmechanism. In that manner, the attorney of the inmate, who may havegained a court order permitting third party calling, can enter thepassword to establish a third party call—either on his own, or by way ofprison facility trunk lines. Also, the called party can be warned thatthe prison is aware the that called party previously completed a thirdparty call, and if that called party does it again, they will be pursuedby government officials. Also, automatic number identification (ANI) canbe used to locate the called party that has completed such third partycalls, so that the called party can be pursued, and forced to stop theoffensive activity.

Typically, in many inmate systems, the pronunciation of inmate's name isstored once in the database and retrieved each time the message isgenerated. This eliminates the risk of an inmate interjecting a shortmessage in place of his/her name. The pronunciation of an inmate's namemay be synthesized from well-known commercially available electronicphoneme sets, or may be reproduced from a voice data file created by theactual inmate or administrator. For example, when an inmate first entersa corrections facility, he/she may be instructed to recite his/her nameinto a voice recorder via a microphone. Then, that voice can be storedpermanently into a file associate with that inmate's calling accountand/or PIN, and can be automatically replayed as desired.

In most cases, the called party is allowed a specified time to determinewhether to accept the call, hang up or press a code, such as GOTU, toinvoke the invention's prospective call screening feature. During thisperiod, TMU 2 monitors the line and transmits any received DTMF tones toCCU 3. As provided herein, that monitoring does not interfere with thedetection of third party calls.

The detection of tones is well-known in the art. In U.S. Pat. No.4,726,057 to Doerry et al., the detection of tones, such as SIT tones,is disclosed, and that patent is hereby incorporated by reference. Inthat patent, several drawings illustrate how tone detecting circuitrymay be formulated.

While the invention has been described with reference to one or morepreferred embodiments, such embodiments are merely exemplary and are notintended to be limiting or represent an exhaustive enumeration of allaspects of the invention. The scope of the invention, therefore, shallbe defined solely by the following claims.

What is claimed is:
 1. A method for detecting call bridging to a thirdparty during a telephone conversation between a calling party and acalled party, comprising: detecting tones originated by the called partyarising during the telephone conversation between the calling party andthe called party; comparing the tones to a predetermined call-bridgingtone set to positively identify an attempt to bridge the telephoneconversation between the calling party and the called party to includethe third party; and executing call-bridging prevention instructions inresponse to an identified call-bridging attempt; wherein thecall-bridging tone set includes at least one of dial tones, busy signaltones, ring signal tones, dual tone multi-frequency (“DTMF”) tones andspecial instruction tones (“SIT”).
 2. The method of claim 1 whereinexecuting the call-bridging prevention instructions comprises:terminating the telephone conversation.
 3. The method of claim 1 whereinexecuting the call-bridging prevention instructions comprises: insertinga warning message into the telephone conversation.
 4. The method ofclaim 1 wherein executing the call-bridging prevention instructionscomprises: recording a telephone number of the third party.
 5. Themethod of claim 1 wherein executing the call-bridging preventioninstructions comprises: comparing a telephone number of the third partyagainst a list of authorized called parties; and terminating thetelephone conversation unless the telephone number of the third partyappears on the list of authorized called parties.
 6. A method fordetecting call bridging to a third party during a telephone conversationbetween a calling party and a called party, comprising: detecting tonesarising during the telephone conversation between the calling party andthe called party; comparing the tones to a predetermined call-bridgingtone set to identify an attempt to bridge the telephone conversationbetween the calling party and the called party to include the thirdparty; and executing call-bridging prevention instructions in responseto an identified call-bridging attempt, wherein executing thecall-bridging prevention instructions comprises: terminating thetelephone conversation unless an authorization code is received from thethird party within a predetermined time period; wherein thecall-bridging tone set includes at least one of dial tones, busy signaltones, ring signal tones, dual tone multi-frequency (“DTMF”) tones andspecial instruction tones (“SIT”).
 7. A method for detecting callbridging to a third party during a telephone conversation between acalling party and a called party, comprising: detecting by an answersupervision board tone frequencies originated by the called partyarising during the telephone conversation between the calling party andthe called party that match a predetermined tone set to identify tonematches; determining by a computer control unit tone characteristics oftone matches received from the answer supervision board; and positivelyidentifying by the computer control unit call-bridging attempts bycomparing tone matches and tone characteristics received from the answersupervision board with a predetermined call-bridging tone data set; andexecuting call-bridging prevention instructions; wherein thepredetermined call-bridging tone data set comprises at least one of dialtones, busy signal tones, ring signal tones, dual tone multi-frequency(“DTMF”) tones and special instruction tones (“SIT”).
 8. The method ofclaim 7 wherein the call-bridging prevention instructions comprises:terminating the telephone conversation by the computer control unitafter identifying a call-bridging attempt.
 9. The method of claim 7wherein the call-bridging prevention instructions comprises: introducinga warning message into the telephone conversation by the computercontrol unit after identifying a call-bridging attempt.
 10. The methodof claim 7 wherein the call-bridging prevention instructions comprises:recording a telephone number of the third party by the computer controlunit after identifying a call-bridging attempt.
 11. The method of claim7 wherein the call-bridging prevention instructions comprises:terminating the telephone conversation by the computer control unitafter identifying a call-bridging attempt unless a telephone number ofthe third party appears on a list of authorized called parties.
 12. Themethod of claim 7 wherein the call-bridging prevention instructionscomprises: terminating the telephone conversation by the computercontrol unit after identifying a call-bridging attempt unless anauthorization code is received within a predetermined time period. 13.The method of claim 7 wherein executing the call-bridging preventioninstructions comprises: storing at least one of a calling party callinghistory or a called party calling history by the computer control unitafter identifying a call-bridging attempt.
 14. A system for detectingcall bridging to a third party during a telephone conversation between acalling party and a called party, comprising: tone detection means formonitoring the telephone conversation to detect bridging tonesoriginated by the called party arising during the telephone conversationbetween the calling party and the called party to include a third partyand sending bridging tone reports to a computer control unit; and thecomputer control unit configured to execute call-bridging preventioninstructions upon receipt of a bridging tone report based on thecomparison of the detected bridging tones to a predeterminedcall-bridging tone set; wherein the tone detection means are configuredto detect bridging tones comprising at least one of dial tones, busysignal tones, ring signal tones, dual tone multi-frequency (“DTMF”)tones and special instruction tones (“SIT”).
 15. The system of claim 14wherein the computer control unit terminates the telephone conversationbetween the first party an d the second party in executing thecall-bridging instructions.
 16. The system of claim 14 wherein thecomputer control unit introduces a warning message into the telephoneconversation in executing the call-bridging instructions.
 17. The systemof claim 14 wherein the computer control unit records a telephone numberof the third party in executing the call-bridging instructions.
 18. Thesystem of claim 14 computer control unit in executing the call-bridginginstructions disconnects the telephone conversation unless the telephonenumber of the third party appears on a list of authorized calledparties.
 19. A system for detecting call bridging to a third partyduring a telephone conversation between a calling party and a calledparty, comprising: a computer control unit configured to executecall-bridging prevention instructions upon receipt of a bridging tonereport; and tone detection means for monitoring the telephoneconversation to detect bridging tones arising during the telephoneconversation between the calling party and the called party and sendingbridging tone reports to a computer control unit; wherein the computercontrol unit in executing call-bridging prevention instructionsterminates the telephone conversation unless an authorization code isreceived within a predetermined time period; wherein the tone detectionmeans are configured to detect bridging tones comprising at least one ofdial tones, busy signal tones, ring signal tones, dual tonemulti-frequency (“DTMF”) tones and special instruction tones (“SIT”).20. A system for detecting call bridging to a third party during atelephone conversation between a calling party and a called party,comprising: an answer supervision board configured to detect tonefrequencies originated by the called party arising during the telephoneconversation between the calling party and the called party that match apredetermined tone set to determine tone matches; and a computer controlunit configured to determine tone characteristics of tone matchesreceived from the answer supervision board, to positively identifycall-bridging attempts by comparing tone matches and tonecharacteristics with a predetermined call-bridging tone data set, and toexecute call bridging prevention instructions after identifying a callbridging attempt, wherein the answer supervision board is configured todetect tone frequencies comprising at least one of dial tones, busysignal tones, ring signal tones, dual tone multi-frequency (“DTMF”)tones, and special instruction tones (“SIT”).
 21. The system of claim 20wherein the computer control unit is further configured to terminate thetelephone conversation between the calling party and the called partyafter identifying a call-bridging attempt.
 22. The system of claim 20wherein the computer control unit is further configured to introduce awarning message into the telephone conversation after identifying acall-bridging attempt.
 23. The system of claim 20 wherein the computercontrol unit is further configured to record a telephone number of thethird party after identifying a call-bridging attempt.
 24. The system ofclaim 20 wherein after identifying a call-bridging attempt the computercontrol unit is further configured to compare a telephone number of thethird party against a list of authorized called parties and disconnectthe telephone conversation unless the telephone number of the thirdparty appears on the list of authorized called parties.
 25. The systemof claim 20 wherein after identifying a call-bridging attempt thecomputer control unit is further configured to terminate the telephoneconversation unless an authorization code is received within apredetermined time period.
 26. The system of claim 20 wherein thecomputer control unit is further configured to process at least one of afirst party calling history or a second party calling history.
 27. Thesystem of claim 20, further comprising: a trunk management unitconfigured to provide telephony services between the calling party andthe called party and further configured to contain the answersupervision board.